This invention relates to a gas-insulated switchgear, in particular to a gas-insulated switchgear including a disconnecting switch and a grounding switch.
FIGS. 7 and 8 are schematic sectional views showing the internal structure of a gas-insulated switchgear 100 of the conventional type that is structurally almost same as the one including a disconnecting switch that is bent at a right angle in the middle as shown in FIG. 1 of Japanese Patent Laid-Open Hei 3-5014 and is equipped with a grounding switch as shown in FIG. 3 of Japanese Published Unexamined Patent Application Sho 60-5711.
The gas-insulated switchgear shown in FIGS. 7 and 8 includes a tank 101 filled with an electrically insulating gas, a first and second conductors 102 and 103 disposed within the tank 101 and disposed at right angles to each other, a disconnecting switch or a disconnector 104 for disconnecting the conductor 102 from the conductor 103 and a grounding switch 105 for grounding the first conductor 102 when the disconnector 104 is opened as illustrated in the figures.
The disconnector 104 is provided with a first fixed contact 107 connected through a connecting section 106 to the tip of the first conductor 102, a second fixed contact 109 connected through a connecting section 108 to the tip of the second conductor 103, a movable contact 110 disposed in the way in which it can move forward to reach to the second fixed contact 109 and bridge the gap between the first fixed contact 107 and the second fixed contact 109 and backward to withdraw from the second fixed contact 109, while always touching the inner surface of the first fixed contact 107, thus putting the first fixed contact 107 in or out of contact with the second fixed contact 109 and a first operating mechanism 111 that is disposed on the outer surface of the wall of the tank 101, extends as far as the inside of the connecting section 106 to be connected to the movable contact 110 and drives the movable contact 110. Both the connecting sections 106 and 108 are held on the tank 101 by an insulation support 112.
The grounding switch 105 is provided with a third fixed contact 113 connected through a connecting section 106 to the first conductor 102 like the first fixed contact 107 described above, a fourth fixed contact 114 disposed on the outer surface of the wall of the tank 101, a second movable contact 115 disposed in the way in which it can move forward to reach to the third fixed contact 113 and bridge the gap between the third fixed contact 113 and the fourth fixed contact 114 and backward to withdraw from the third fixed contact 113, while always touching the inner surface of the fourth fixed contact 114, thus putting the fourth fixed contact 114 in or out of contact with the third fixed contact 113 and a second operating mechanism 116 that is disposed on the outer surface of the wall of the tank 101 and is connected to the second movable contact 115 for driving the movable contact 115. The tank 101 is provided with insulated supports 121 for the connecting sections 106 and 108, as well as a plurality of manholes 117 for maintenance and inspection.
In disconnectors for gas-insulated switchgears of the conventional type, the electrodes at both the movable and fixed sides are held within the tank by insulation supports and the grounding switch is fastened to the tank in the way in which a movable contact can move to be connected to the electrodes. Gas-insulated switchgears including such disconnectors and grounding switches often suffer from a poor work efficiency in performing the setting-up of the parts that is made primarily on the tank as a consequence of a narrow space within the tank, and it is necessary to provide such switchgears with a peep hole for adjusting and checking the connection between electrodes. Further, conventional switchgears need to be provided with such parts as a shaft seal, fastening flanges and operation devices for connecting the disconnector and the grounding switch separately to their respective operating mechanisms disposed outside the tank, thus making it difficult to omit such parts.